JPS63133223A - Electronic equipment - Google Patents

Abstract

PURPOSE:To prevent interruption of operation due to reading action by using a direction detecting means whose output is changed to an H level from an L level when a fact that the output of a comparison means is changed to an OFF state from an ON state is detected. CONSTITUTION:When a switch 1 is pushed up to a time point C from a time point B of a clock CLK, a comparison means 3 outputs an ON state since a reading means 2 reads twice continuously the ON state at a time point C. Then the switch 1 is turned off and the means 2 is also turned off at a time point D. At a time point E the means 2 outputs an OFF state again, and therefore the means 3 outputs an OFF state. A direction detecting means 5 outputs an H level in response to a fact that the output of the means 3 is changed to an ON state from an OFF state. A control means 6 reads the output of the means 5 at a time point G to decide that the switch 1 is pushed and releases a communication state. In such a case, a reset signal RST is outputs and the means 5 is changed to an L level. In such a constitution, it is not required for the means 6 to interrupt printing. Thus the printing speed is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a central processing unit (hereinafter abbreviated as CPU).
The present invention relates to an electronic device that operates in response to a read signal.

2. Description of the Related Art Conventionally, there have been devices that perform calculations using a CPU to perform various tasks. In order to prevent jitter, such a device reads the switch state so that it is determined that the switch is in the ON state only when the ON state is read twice in a row.

Hereinafter, one of these devices, a printer having a CPU, will be described.

FIG. 5 shows a circuit block of a conventional printer, in which 1 is a switch for setting a state in which it can communicate with a host computer (not shown), 2 is a clock signal CLK that is manually input, Reading means 3 reads the state of switch 1 at regular time intervals; 3 compares the signal read by reading means 2 with the signal read previously by reading means 2, and determines whether both of the two signals are in the ON state or OFF; A comparison means outputs the state when the state is indicated, and 4 is a control including a printing means (not shown in the figure), a means of communicating with the host computer (not shown in the figure), etc. It is a means.

The operation of the conventional printer configured as described above will be explained below using the timing chart shown in FIG.

First, at time point A, the control means 4 is in communication with the host computer, and is in a state in which information is input from the host computer and printing is performed. Also, at this time, switch 1 is not pressed.

Now, for some reason, the printer user is
Suppose that you try to disconnect the communication between the host computer and the printer in order to interrupt printing, and press switch 1 from point A to point T.

First, the reading means 2 reads the ON state at the rising edge of the clock signal at time point A.

At the next point in time, the reading means 2 reads the ON state again. At this time, since the reading means 2 has read the ON state twice in succession, the comparing means 3 outputs the ON state.

Next, during the process, the switch becomes OFF, and the reading means 2 also outputs the OFF state.

Next, at time O, the reading means 2 outputs the OFF state again, so the comparing means 3 outputs the OFF state.

In this way, the signal is in the ON state from time point 1 to time point O, and is output to the control means 4.

The control means 4 reads this output at regular time intervals, detects the ON state at a point in time between time 0 and time 0, and releases the communication state with the host computer.

Problems to be Solved by the Invention However, in the conventional configuration described above, even if the switch 1 is pressed for a short time and the ON state of the output of the comparison means 3 lasts only for a short time interval, the control means 4 does not turn on the output of the comparison means 3.
In order to detect the status, it is necessary to read the output of the comparison means 3 at intervals of two cycles or less of the clock signal, but in order to read the output, it is necessary to interrupt printing or use some method of free time. However, there were problems in that the printing speed was slow and the overall control structure was complicated.

To solve this problem, if the switch is pressed for a short time, it can be ignored, but in this case, even if the user thinks the switch is pressed, the printer will not accept it, so the user will have to repeat it many times. This results in a problem that the operability is very poor since the user has to press a switch.

Means for Solving Problems The present invention compares the signal read by the reading means with the previous signal read, and if the two input signals are in different states, the signal is the same as the previous signal. a comparison means which outputs a signal corresponding to the state of the input signal when the two input signals are in the same state, and a comparison means which outputs a signal corresponding to the state of the input signal when the two input signals are in the same state; The present invention is equipped with a direction detecting means that changes the state of an output signal and continues to output it in response to only one of the cases where the state changes from the second state to the first state.

Effect: With the above configuration, even if the output of the comparing means maintains a specific state only for a very short period of time, the detecting means detects that the state of the comparing means itself has changed.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

1st V! J is a circuit block diagram of a printer according to an embodiment of the present invention, in which 1 is a switch, 2 is a reading means, and 3 is a comparison means, which are the same as those in the conventional example. 5, when it is detected that the output of the comparison means 3 changes from the ON state to the OFF state, the output becomes OV (hereinafter referred to as
It is abbreviated as L level. ) to +5V (hereinafter abbreviated to I level).

), 6 includes a printing means (omitted in the figure), a communication means with the host computer (not shown in the figure), etc., and an interwoven request terminal (hereinafter, IRQ terminal). ), the output of the direction detection means 5 is read, and the output of the direction detection means 5 is read.
This is a control means that outputs a reset signal R3T that returns the signal to the initial state of L level.

The operation of the printer of this embodiment configured as described above will be explained below using the timing diagram of FIG. 2.

As in the conventional example, the switch 1 is pressed from time 1 to time 3, and the output of the comparison means 3 is in the ON state from time 1 to time 0.

At this point, the direction detection means 5 outputs an H level in response to the output of the comparison means 3 changing from the OFF state to the ON state.

At time point K, the control means 6 reads the output of the direction detection means 5, determines that the switch 1 has been pressed, and releases the communication state with the host computer. At this time, the direction detection means 5 returns to the L level in order to output the reset signal R8T.

In this embodiment, the output of the direction detection means 5 returns to the L level only after being read by the control means 6.
There is no need to read the state of the direction detecting means 6 at fixed time intervals, and the switch 1 can be read using the idle time during printing.
You can indirectly see whether or not is pressed. Therefore, there is no need to interrupt printing, and printing speed can be increased.

FIG. 3 is a circuit block diagram of a printer in another embodiment, in which 7 is connected to a switch (not shown in the figure), and the state of the switch is read every time the clock signal CLK rises. , a jitter prevention circuit that outputs a signal corresponding to the state when it is equal to the previously read state; 8 is a jitter prevention circuit that outputs a signal corresponding to that state; 8 is a jitter prevention circuit that outputs a signal corresponding to the state read previously; This is a pulse direction detection circuit that becomes 1 level in either case when it changes to the ON state, and the output of the pulse direction detection circuit is output to a control circuit (not shown in the figure).

) interrupt signal (hereinafter abbreviated as IRQ signal)
becomes. Reference numeral 9 denotes a memory, and the memory 9 includes a direction specifying register 9a% for specifying in which direction the pulse direction detecting circuit 8 is activated and an IRQ mask register for disabling the output of the pulse direction detecting circuit 8. 9b
.

and an IRQ register 9c in which IRQ signals are stored. 10 is a NAND gate for invalidating the output of the IRQ signal.

FIG. 4 is an actual circuit diagram of the printer in this embodiment, and the jitter prevention circuit 7 includes D flip-flop circuits 11 and 12, NOR gates 13, 15, and
It is composed of an ND gate 14. Further, the pulse direction detection circuit 8 includes a flip-flop circuit 17, NOR gates 19, 21, and 22, and NAND gates 18 and 20. 23.24 is the read signal CP
A transistor for outputting the input signal 1N as output data DB when REI is at H level, 25.26 is a special gutter prevention circuit 7 when read signal CI'RE2 is at H level.
Transistors 27 and 28 are transistors for outputting the output of the pulse direction detection circuit 8 as output data DB when the read signal CPRE3 is at the Tr level. In the figure, TMI and TM2 are timing signals, DRE is a direction designation signal from the direction designation register 9a, RQM is an interrupt signal output prohibition signal from the IRQ mask register, and IRQ is i
+J control means interrupt port (omitted in the figure).

) and R3T indicate a reset signal for resetting the D flip-flop circuits 11 and 12 and the NOR gates 13 and 22.

The operation of the printer of this embodiment configured as described above will be described below.

As in the first embodiment, the jitter prevention circuit 7 reads the state of the input signal IN every time the timing signal TMI changes from L level to 1-level, and when the same state is read twice in a row, the Output.

Next, the pulse direction detection circuit 8 detects the direction in which the output of the jitter prevention circuit 7 changes, that is, changes from an ON state to an OFF state, according to the timing signal TM2.
It detects the direction in which it changes from the ON state to the ON state, and becomes the I level. This direction is specified by the direction specification register 9.
Specified by a.

Interrupt prohibition is specified in IRQ mask register 9b,
If the interrupt output disabling signal RQM is not output, the output of the pulse direction detection circuit 8 is output as the interrupt signal IRQ to the interrupt port of the control circuit. At the same time, the state of this signal is stored in the IRQ register.

The control circuit releases the communication state with the host computer in response to the interrupt signal IRQ generated in this manner.

Note that in this embodiment, the input signal IN is inputted by specifying one of CPREI to CPRE3.

Output of the jitter prevention circuit 7, one of the interrupt signals
Since the control circuit can read one as the output data DB, it can not only read the switch that is unlikely to be pressed repeatedly in a short period of time, such as a switch to cancel the communication state with the host computer. It can also be used to read the status of switches that are repeatedly operated and the status of sensors such as photosensors that detect when paper runs out.

Effects of the Invention The present invention compares the signal read by the reading means with the previous signal read, and if the two input signals are in different states, outputs the same signal as the previous signal, and a comparison means that outputs a signal corresponding to the state of the input signal when the two input signals are in the same state; and a comparison means that outputs a signal corresponding to the state of the input signal when the two input signals are in the same state; The device is equipped with a direction detecting means that responds only to one of the cases where the state of the output signal changes from the first state to the first state, and continues to output the state of the output signal. The IIF control circuit does not need to read the output of the comparison means at short time intervals because the change in the state of the comparison means itself is detected by the detection means and continues to be output. (If you read the output of the detection means at an arbitrary time, you will know that the signal has changed, so the operation will not be interrupted for reading (), the speed of the device can be increased. Since the priority of control can be lowered, the overall control structure can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram of a printer in one embodiment of the present invention, FIG. 2 is a timing chart of the same, FIG. 3 is a circuit block diagram of a printer in another embodiment, and FIG. 4 is an actual circuit diagram of the same. FIG. 5 is a circuit block diagram of a conventional printer, and FIG. 6 is a timing chart thereof. 1...Switch, 2...Reading means, 3...
・Comparison means, 5...Direction detection means, 6...Control means, 7...Chuck-prevention circuit, 8...Pulse direction detection circuit, 10...Name of NAND gate agent Patent attorney Nakao Toshio One Idiot Figure 2 cQcz '3

Claims (1)

[Claims] A reading means for reading an input signal that can take two states at regular time intervals, and a signal read by the reading means is compared with a previously read signal, and if the two input signals are in different states, 1 If the same signal as the previous signal is output and the two input signals are in the same state,
comparison means for outputting a signal corresponding to the state of the input signal;
The state of the output signal is changed in response to only one of the cases where the output of the comparison means changes from the first state to the second state or from the second state to the first state. An electronic device characterized by having a direction detection means that continuously changes and outputs the output.